NASHVILLE — Millions of motorists traveling over the weekend paid the most expensive Labor Day gas prices in four years.

Now, prices might become even more expensive thanks to Tropical Storm Gordon, which could impact refineries, depending on its path and strength at landfall.

“It’s too early to know just how much of an impact — if any — Gordon will have on prices at the pump,” said Mark Jenkins, AAA spokesman, in a press release. “Market watchers will pay close attention to how refineries respond to this storm. Any supply outages would likely cause prices to climb.”

Gas prices in Tennessee are slightly higher than a week ago, AAA reported. The state average of $2.59 per gallon is a half-cent more than last week, 7 cents less than last month and 6 cents more than this time last year.

A storm’s coming

The National Hurricane Center expects Gordon to strengthen into a hurricane before making landfall somewhere between the Louisiana and Florida coastlines.

So far, the storm has not affected gas prices, but that would change if refineries suffer damage or go offline. Refineries in Louisiana and Mississippi began making preparations for the storm on Monday, AAA reported.

The Gulf Coast is home to nearly half (45 percent) of the nation’s refinery capacity, according to AAA. Last year, pump prices surged after Hurricane Harvey made landfall in Texas, causing mass flooding and refinery outages.

Most expensive gas prices in the state

• Jackson ($2.66)

• Nashville ($2.64)

• Memphis ($2.62)

Least expensive gas prices in the state

• Cleveland ($2.46)

• Chattanooga ($2.50)

• Kingsport-Bristol ($2.53)

Summer trends

Summer gas prices this year were the highest in four years, according to AAA. From June 1-Aug. 31, the price for a gallon of regular unleaded averaged $2.87 nationwide and $2.63 in Tennessee.

Crude oil prices averaged $68.56 per barrel this summer, nearly $20 more than the summer 2016. This increase raised the price of gasoline production, AAA reported.